This invention relates to an attachment for a vacuum pump. In particular, the invention relates to an attachment for a vacuum gun, for evacuating fluid from a reservoir of fluid and for containing the fluid that has been evacuated.
The invention has been developed primarily for evacuating brake fluid from the brake system of a vehicle and will therefore be described in this context. It is to be appreciated, however, that the invention may have other uses.
Venturi motors are well known in the art for their use in vacuum pumps. Venturi motors typically comprise a tube with a short constriction in the middle (a throat) between two tapered ends (an intake and an outlet). The throat causes a drop in pressure in the fluid flowing through it. Compressed air or other compressed fluids may be used to power such motors. Typically, the intake of the venturi tube is positioned adjacent an inlet through which compressed air enters the venturi motor, and fluid that is to be evacuated from a reservoir of fluid is introduced through a port (from hereon referred to as a vacuum port) which channels the fluid between the air inlet and throat. As compressed air exits the inlet it expands and increases in velocity before entering the throat of the venturi tube. This creates a vacuum or negative pressure at the vacuum port so that the fluid is drawn into the venturi tube.
There are presently a number of methods for bleeding brake fluid from bleeder ports of vehicle brake systems. One of these methods involves attaching a device generally known as a pressure bleeder to the master cylinder of the vehicle and pressurizing the brake system. Once under pressure, each bleeder port of the brake system is opened systematically to bleed the brakes. Another method entails the use of a device generally known as a vacuum bleeder. This device attaches to a bleeder port of the vehicle and draws brake fluid from the master cylinder.
The devices employed in bleeding vehicle brake systems have disadvantages in that they may be difficult to use, namely that they may be heavy and difficult to maneuver into position for bleeding.
It is therefore an object of the present invention to provide an attachment for a vacuum pump that minimises the disadvantages of the devices referred to above, or provides the public with a useful or commercial choice.
According to a first aspect of the present invention there is provided an attachment for a vacuum pump, for evacuating and containing a fluid from a reservoir of fluid, said attachment having:
a body with an inlet for the fluid and an outlet, and the outlet is attachable to the pump;
a coupling intermediate the inlet and outlet;
a container which is releasably attachable to the coupling;
a first passage extending between the inlet and the container;
a second passage extending between the container and the outlet; and
an operating member associated with at least one of the said passages and which is moveable to either close or open the associated passage, and when a vacuum is generated within the attachment by the pump and the operating member is in the open position, the fluid may be collected within the container.
The attachment may have a float valve located within the second passage for blocking this passage when the container is full of fluid.
The operating member may consist of a tap moveable between the open and closed positions. Preferably, the tap is able to close or open both of the said passages. The tap may be received within a spigot extending from the attachment body. The tap and spigot may form part of the first and/or second passages.
The first passage may be provided in part by a delivery tube extending between the inlet and the spigot. Preferably, the delivery tube comprises two or more detachable pieces.
The inlet of the attachment body may be at the end of a nozzle. The nozzle and a piece of the delivery tube may be detachable from the remainder of the body. The nozzle may frictionally engage the remainder of the body and delivery tube. The body and nozzle may be attachable by any other suitable means. The attachment may further have a hose that is attachable to the nozzle, for communicating fluid from the reservoir to the inlet.
The coupling which allows the container to be secured to the body may be a screw threaded coupling, a snap fitting coupling, a bayonet coupling or any other suitable coupling. Preferably, the coupling has a seal such that the fluid cannot leak from the container by accident.
The container may have reinforcing structures such as ribs to prevent walls of the container from collapsing under negative pressure.
According to a second aspect of the present invention there is provided a vacuum gun assembly for evacuating and containing a first fluid from a reservoir of fluid, said gun assembly comprising a vacuum gun and an attachment for the gun, with said gun having:
a body having a grip, a barrel and a bore extending through the barrel from a front end to a rear end of the gun;
a venturi motor within the bore; and
an inlet into the body for a second fluid which powers the venturi motor and the second fluid discharges through the rear end of the gun so that a vacuum is generated within the attachment,
with said attachment having:
a body with an inlet for the first fluid and an outlet, and the outlet is attachable to the front end of the gun;
a coupling intermediate the inlet and outlet;
a container which is releasably attachable to the coupling;
a first passage extending between the inlet and the container;
a second passage extending between the container and the outlet; and
an operating member associated with at least one of the passages and which is moveable to either close or open the associated passage, and when a vacuum is generated within the attachment by the pump and the operating member is in the open position, the fluid may be collected within the container.
The outlet of the attachment may be of sufficient diameter to seal around the front end of the gun. Optionally, other means for attaching the attachment to the gun may be used.
The gun may have a perforated plate covering the discharge end of the venturi motor for reducing the noise of the second fluid leaving the gun. The gun may have an insert adjacent the perforated plate for further reducing the noise of the second fluid prior to discharge. The insert is preferably porous and consists of foam. The foam and plate may be directly coupled to the venturi motor.
The rear end of the gun may be fitted with a hose in order to direct the discharged fluid away from an operator of the gun assembly.
Preferably, the gun is of the type disclosed in Patent Specification WO 99/20399.